The zona incerta stands out sharply as a brain structure that may be subject to the four-color topological constraints described by Robert Glassman. It seems to be made up of four loosely defined and heavily interconnected cyto-architectonic sectors (rostral, caudal, dorsal and ventral). Furthermore, four diverse functions have been associated with the zona incerta, and some evidence suggests that each of these functions can be mapped to its own sector (perhaps with some overlap into other sectors. Mitrofanis, 2005).

The global function of the zona incerta can be seen as linking diverse sensory channels to appropriate response systems, namely visceral, arousal, attention and postural-locomotive systems. These four systems can be assigned to fuzzy PAEI sets as follows:

The superior colliculus has been described as having two modes: an event mode eliciting visual tracking, and an emergency mode triggering defensive avoidance or flight. (Dean et al., 1989). The zona incerta may participate in permitting and/or inhibiting visual tracking guided by sensations on the body, depending on the degree of defensive activation.

While zona incerta functions are a far cry from the higher workings of human personality and temperament, they cluster along PAEI lines of activity, monitoring/defensive avoidance, degrees of alertness and awakening, and social/visceral functioning (which are basically identical for infant mammals). Furthermore, the connections of the zona incerta are very extensive, synapsing along the vertical extent of the brain from cerebral cortex to spinal cord. If its inputs and outputs are topographically mapped to any extent, this would argue for the relevance of a fourfold organizational scheme for the neuraxis.